TextBox focus listener : TextBox « Windows Presentation Foundation « VB.Net Tutorial

1. VB.Net Tutorial
2. Windows Presentation Foundation
3. TextBox

<Window x:Class="WpfApplication1.Window1"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    xmlns:custom="clr-namespace:WpfApplication1"
    Title="Keyboard Sample" Height="250" Width="300">
    <StackPanel>
        <Label Name="lblNumberOfTargetHits" HorizontalAlignment="Center"/>
        <TextBox Name="txtTargetKey" GotKeyboardFocus="TextBoxGotKeyboardFocus" LostKeyboardFocus="TextBoxLostKeyboardFocus">A</TextBox>
        <TextBox TextWrapping="Wrap" GotKeyboardFocus="TextBoxGotKeyboardFocus" LostKeyboardFocus="TextBoxLostKeyboardFocus" KeyDown="SourceTextKeyDown"/>
    </StackPanel>

</Window>


//File:Window.xaml.vb

Imports System
Imports System.Windows
Imports System.Windows.Controls
Imports System.Windows.Data
Imports System.Windows.Documents
Imports System.Windows.Media
Imports System.Windows.Media.Imaging
Imports System.Windows.Shapes
Imports System.Windows.Annotations
Imports System.Windows.Input
Namespace WpfApplication1
  Public Partial Class Window1
    Inherits Window

    Public Sub New()
      InitializeComponent()
    End Sub

    Private Sub TextBoxGotKeyboardFocus(sender As Object, e As KeyboardFocusChangedEventArgs)
      Dim source As TextBox = TryCast(e.Source, TextBox)
      If source IsNot Nothing Then
        source.Background = Brushes.LightBlue
        source.Clear()
      End If
    End Sub
    Private Sub TextBoxLostKeyboardFocus(sender As Object, e As KeyboardFocusChangedEventArgs)
      Dim source As TextBox = TryCast(e.Source, TextBox)

      If source IsNot Nothing Then
        source.Background = Brushes.White
      End If
    End Sub
    Private Sub SourceTextKeyDown(sender As Object, e As KeyEventArgs)
      Dim converter As New KeyConverter()
      Dim target As Key = Key.None

      If txtTargetKey.Text.Length = 1 Then
        target = CType(converter.ConvertFromString(txtTargetKey.Text), Key)
      End If
    End Sub
  End Class
End Namespace

16.4.TextBox
	16.4.1.	You cannot use TextBox and Image at the same time for Button Content
	16.4.2.	Single line and Multiline TextBox
	16.4.3.	TextBox Column
	16.4.4.	Bind value to TextBox
	16.4.5.	An upside down TextBox
	16.4.6.	Style with Data Trigger for TextBox
	16.4.7.	TextBox with custom ErrorTemplate and ToolTip
	16.4.8.	TextBox uses the ExceptionValidationRule and UpdateSourceExceptionFilter handler
	16.4.9.	TextBox with UpdateSourceExceptionFilter handler
	16.4.10.	TextBox focus listener
	16.4.11.	TextBox MouseLeftButtonDown action and PreviewMouseLeftButtonDown action
	16.4.12.	Mark the text control as being changed to prevent any text content or selection changed events
	16.4.13.	Listen to TextBox text changed event
	16.4.14.	Handler for the PreviewKeyDown event on the TextBox
	16.4.15.	Format TextBox with MenuItem: normal, bold, italic
	16.4.16.	TextBox: set text, select all, clear, prepend, insert, append, cut, paste, undo
	16.4.17.	Set TextBox to editable
	16.4.18.	Scroll TextBox
	16.4.19.	Use TextBox.CommandBindingst to bind command
	16.4.20.	Use Dictionary to record which textbox has been changed and not saved
	16.4.21.	Set TextBox ContextMenu to null
	16.4.22.	TextBox Selection start, end and selected text
	16.4.23.	Scrollable TextBox Column
	16.4.24.	Check Spelling Error